Superregenerative receiver



Dec. 25, 1951 w. R. KOCH SUPERREGENERATIVE RECEIVER 2 SHEETS-SHEET lFiled Jan.28, 1948 1m 0 M v WM WP. m ,M .w M M fY We Em /A l?. E AMP!Vil/EINER Dec; 25, 1951 Filed Jan. 28, 1948 w. R. KOCH 2,580,028

SUPERREGENERATIVE RECEIVER 2 SI-IEETS-SliEET 2 ATTORNEY Patented Dec.25, 1951 Winfield R. Koch, Marlton, N.

Radio Corporation of America,

of Delaware J., assignor to a corporation Application January 28, 1948,Serial No. 4,872

2 claims. (c1. 25o-72o) f 1 This invention relates to super-regenerativereceivers, and particularly to regenerative amplifiers having eitherself-quenching or separate quenching action suitable particularly foruse in an angle-modulated carrier-wave receiver, as

well as to novel methods of demodulating a modulated carrier wave byregeneration.

Super-regenerative receivers including a regenerative detector are wellknownfin the art. A regenerative detector may be ofthe selfquenchingtype wherein a circuit such as a resistor-condenser network is providedto interrupt or quench the regeneration of the input wave preferably ata super-audible frequency, or a separate quench oscillator may beprovided for periodically interrupting the regeneration of the inputWave at a super-audible frequency. In accordance with conventionalpractice the output current of a regenerative detector is integrated,thereby to demodulate directly the modulated carrier wave and to derivethe modulation signal. A super-regenerative receiver may be utilized forreceiving either an angle-modulated or an amplitude-modulated (AM)carrier wave. If an angle-modulated or frequency-modulated (FM) carrierwave is received, the signal input circuit of the regenerative detectoris tuned slightly off the mean or center frequency so that the signalinput circuit functions as a frequency-discriminator network.

A regenerative detector, accordingly, develops directly the modulationsignal. On the other hand, in United States Patent No. 2,410,981 grantedon November 12, 1946, to W. R. Koch and entitled Super-RegenerativeReceiver Circui a regenerative amplier of the self-quenching type hasbeen disclosed for use in a super-regenerative receiver. It has beenshown therein that the quench current derived from a regenerativeamplifier of the self-quenching type is frequently modulated inaccordance with the angle or amplitude modulation of the input carrierwave, and that this frequency-modulated quench current may betransformed by a frequency-discriminator network into a correspondingamplitilde-modulated quench current which may subsequently be detectedby a separate detector. This may be effected by mistuning the detectorinput circuit. In such a system, the tuning of the regenerativeamplifier input circuit and of the detector input circuit are mutuallydependent. It may be necessary to adjust the tuning of the two inputcircuits repeatedly before the modulation signal may be properlyreproduced.

Itis,accordingly, an object of the present in-Y ventionL to provide animproved receiver embodying' a regenerative amplii'ler and a separatedetector in which the tuning of the amplifier input circuit isindependent of the tuning of the detector input circuit.

Another object of the present invention is to provide a novel method ofdemodulating either an angle-modulated or an amplitude-modulated carrierwave by regeneration.

Still vanother object of the present invention is to provide an improvedconverter including a regenerative amplifier for converting directly anangle-modulated or amplitude-modulated ultrahigh frequency wave into anamplitude-modulated low-frequency wave without the necessity ofswitching or adjusting any circuit elements other than tuning thereceiver to the proper wave.

A further object of the invention is to provide a simplified FM adaptorfor receiving angle-modulated carrier waves with a. conventionalamplitude-modulated carrier-wave receiver.

A still further object is to provide such an adaptor which utilizeseither a self-quenching regenerative amplifier or a regenerativeamplifier employing a. separate quench oscillator to develop a modulatedquench current, a harmonic of which is applied to the input circuit of aconventional broadcast band AM receiver for further amplification andsubsequent detection.

Still another object of the invention is to provide, for anamplitude-modulated carrier-wave receiver', `a simple, inexpensiveadaptor for receiving angle-modulated carrier waves wherein thehigh-frequency angle-modulated carrier wave is directly translated intoa modulated low-frequency quench current which may be reproduced by theamplitude-modulated carrier-wave receiver. Y

' In brief, a super-regenerative receiver for demodulating a modulatedcarrier wave in accordance with the present invention comprises aregenerative amplifier on which the modulated carrier `wave isimpressed. A quench oscillator is coupled to 'the regenerative amplifierfor periodically initiating and interrupting regeneration of the carrierwave at a predetermined frequency which is preferably a super-audiblefrequency. A quench frequency current is consequently derived from theregenerative amplifier which has its amplitude modulated in response tovariations of the amplitude of the carrier wave. The amplitude-modulatedquench current may then be applied to a detector and demodulated toderive the modulation signal corresponding to the modulation originallypresent. on the carrier tude-modulated carrier-wave broadcast receiver.y

In that case, the super-regenerative receiver may have either aself-quenching regenerative amplifier or a regenerative amplifier of thetype ernvploying a separate quenchingoscillator."

In accordance with the present inventionaV method of demodulating amodulated carrier wave comprises the steps of regenerating the carrierwave. and cyclically interrupting theregeneration at a constantfrequencywhich preferably is a super-audible frequency to Yproduce aquench current whose amplitude is determined by the ainplituderof thecarrier wave. Finally the amplitude-modulated quench current yisdemodulated to develop the modulation signal.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claini's. The inventionitself, however, both as toits organization and method of operation, aswell as Vadditional objects and advantages thereof, will best beunderstood from the following Adescription when read in connection withthe accompanying drawings, in'which: Y Y Fig. 1 is a circuit diagram ofa super-regenerative receiver embodying the present invention andincluding a regenerative amplifier of the type having a separate quenchoscillator;

Fig. 2/ is a graph showing curves Vreferred to in explaining theoperation of the regenerative amplier of Fig. vl;V l

Fig. V3 is a circuit diagram of an angle-inodu lated carrier-waveadaptor and la conventional amplitude-modulated carrier-'wave broadcastreceiver shown inblock'forni, the adaptor 'includi'ng Ya separate quenchregenerative amplifier in accordance with the present invention;

Figl 4 is a circuit diagram Vof modified anglemodulatedcarrier-wa'veadaptor in accordance with the invention and including a self-quenchf'ingf'regenerative amplifier; and

Fig. 5 is a graph showing curves referred tofin explaining 'theoperation of the self-quenching regenerative amplifier 'of Fig. 4. 1

Referring now to the drawings'and particularly to Fig. 1, there isillustrated a super-regenerative receiver including regenerativeamplifier I which is controlled by quenchnoscillator 2.v As'will bevexplained in Hdetail hereinafter,v the quench cur'- rent derived fromregenerative amplifier Iv has its amplitude modulated in accordance'vwith'the received signal. The modulation signal which may be an audiosignal, is` derived from detector 3. The audio signal may -be amplifiedby audio an'iplier' and reproduced by loud speaker E.

The input signal lis impressed upon primary coil I. The input signal mayeither be an ampli-4 tude-modulated carrier wave, orvalternatively, anangle-modulated carrier wave. In the latter case the input signal maybetransformed into a corresponding amplitude-modulated carrier wave bydetuning input circuit 'I from the mean car:` rier frequency so that itfunctions as a frequencydiscriminator network. As used herein, thegeneric expression angle modulation or anglemodulated Wave is intendedto include either frequency or phase modulation or a modulation whichcontains components resembling both frequency and'phase modulation andis, therefore, a hybrid modulation. e

n Input circuit I'includes secondary coil 8 inductively coupled toprimary coil 6, and condenser I0 which may be variable, as shown. In-

put circuit 1 has its high alternating-potential terminal-connected tocontrol grid I2 of amplifier section `II by grid coupling condenser I3bypassed toy groundby grid leak resistor I4. Ampliner sectionII furtherincludes cathode I5 connected to ground through cathode resistor I6A`and-'fanodeI7 :connected to a suitable positive voltage Vsourceindicated at +B. Regenerative amplier vI includes another amplifiersection 23 having cathode 2i, control grid 22 and anode 23. Cathode 2I'is' connectedv 'to vcathode I5. vGrid leak resistor Ziifis connectedbetween control grid 22 and ground.' Anode A23 lis connected to thepositiveI voltage source +B through anode resfistor-25.'` vAno'de 23 iscoupled to control grid I2 VAthrough blocking condenser and Ygridcoupling condenser I3. The 'outputsignal may be derived across cathoderesistor I6 and obtained from lead 21. n

Regenerative vamplifier I 'including vamplifier sections Il and 20 iscontrolled by quench oscillator 2 comprising oscillator rsections 30 and3I. Oscillator'section 30 "includes'cathode 32, control grid 33 andVanode 34 While oscillator section 3l is provided with/cathode 35,control grid 35, and anode 31. 'Cathodes 32 'and k35 are tied togetherand connected to groundV through common cathode .resistor 38. V"Controlgrid 33 is grounded as showniwhilejanode 34 'is connected to thepositive voltage supply +B through anode resistor 49. Anode 31 isYdirectly vconnected to the positive voltages'upply +B. Control lgrid 33is connected to ground'throulgh resistor 4I, bypassed by condenser 42.Resistor -43 and condenser 44, arranged in "series, connect fanode 34 tocontrol grid 36.' Anode 3L! of quenchoscillator 2 is connected tocontrol grid 22 -of regenerative'ampli-- ner `I through resistor 45 andcondenser 46 ar` ranged 'in' series.`

As previously explained, the input signal iinp'ress'ed'upon inputcircuit 'I l'may be an amplitude-inedulated carrier wave. In that case,in put circuit '1 is 'tuned 'to the frequency of theamplitude-"modulated wave. Alternatively, an angle-modulated carrierwave may be impressed upon 'input circuit 1; Input circuit I may now betuned to a frequency which lis on the center frequency of the carrierwave so that Vthe slope of the resonant curve ofthe input circuit willtrans form the 'angle-modulated 'carrier 'wave into a 'co'rrespondi'ngamplitude-modulated carrier wave infvth/e manner explained in the Kochpatent referred to above. Input circuit i now functions as Vafr'e'quency-discriminator network.

Regenerative'amplifier vI and its quench oscillator 2ope`r`at'e inv thefollowing manner. rLet it be assumed that oscillator sectionv Si isconductingspace current at an yincreasing rate. The current thus flowingthrough cathode resistor 38 will'raise the potential of both cathodes 32and 35. VSince 'control grid 33 is always at ground potential, thehigher potential of cathode 32 will prevent oscillator section 30 'fromconducting space current. Y Quench I oscillator 2 operates -in 5. themanner of a relaxation oscillator, and accordingly, the current throughoscillator section 3| increases until the discharge suddenly stops. Inthe absence of space current through oscillator sections 3c and 3|, thepotential of cathode 32 approaches ground potential, thereby permittingspace current to How through oscillator section 30. The current newflowing through anode resistor 45 causes a voltage drop thereacrosswhich is impressed through coupling condenser 44 and resistor 43 oncontrol grid 35, thereby preventing oscillator section 3| fromconducting space current.

A substantially square-topped series of pulses shown at 48 may bederived across anode resistor 4B and is impressed through fllterresistor 45 and coupling condenser 46 r on control grid 22v of amplifiersection 2c. The frequency of pulses 48 is determined by the circuitconstantsv of the series network consisting of resistor 43, condenser44, and the parallel network comprising resistor 4|, condenser 42. Inother words, the

two networks consisting of resistor 43, condenser 44 and of resistor 4|,condenser 42 function as a voltage divider and phaser shifter. At acertain frequency determined by the constants of the two networks, therewill be no phase shift between the voltage of anode 34 and that ofcontrol grid 38. Quench oscillator 2 will oscillate at that frequencyfor controlling the regeneration of regenerative ampliiier Whenever apositive pulse 45 developed across anode resistor 4i! is impressed uponcontrol grid 22, amplifier section 20 will conduct space current. Atthat time space current may also flow through amplifier section i undervthe control of the input signal. Hence, amplifier sections Ii and 2Dboth conduct space current and amplier may oscillate. However, as soonas oscillator section 3D again conducts space current, a negativevoltage is impressed upon control grid 22, which, in turn, willextinguish amplifier section 20. Accordingly, the Voltage of anode 23rises and this positive voltage is impressed through condensers 25 andI3 upon control grid |2 of amplifier section thereby permitting the flowof space current through ampliiier section However, since amplifiersection 2U is cut off, amplifier can no longer oscillate. Theregeneration of the modulated carrier Wave impressed upon input circuiti is accordingly cyclically initiated and interrupted by quenchoscillator 2, and its frequency is determined by the circuit constantsof the oscillator.

The mode of operation of regenerative amplifier l may be explained byreference to Fig. 2 wherein the Voltage of control grid i2 of ampliiiersection is plotted against time. Thus, curve 50 indicates the directcurrent voltage of controlV grid |2. When amplifier section 2!) isrendered conducting, the direct current of grid |2 becomes more negativeas shown by curve 5S. The regeneration of the modulated carrier wavewill build up an oscillation in input circuit 1 at the carrier frequencywhich is superimposed on the direct current grid voltage as illustratedby curve After a certain period of time determined' by quench oscillator2 and indicated by line 52 in Fig. 2, amplifier section 2|! is renderednon-conductive. The direct current'grid .voltage 5B decreasesexponentially with time ata rate determined by the time constants ofcoupling condenser |3 and grid leak resistor I4. During that time, :theloscillation previously built up in input circuit 1 atthe frequency ofthe input wave is c? rapidly damped because regenerative ampliiier nolonger oscillates and hence 'can no longer supply energy to inputcircuit Curve 53 of Fig. 2 illustrates the modulated carrier waveWhich-is impressed upon input circuit v1 and consequently on controlgrid l2. Although input wave 53 will be continuously irnpressed oncontrol grid |2, it has only been shown for a portion of the quenchcycle in order to avoid confusion. At a predetermined instant, shown byline 54, amplifier section 20 is again rendered conductive by quenchoscillator 2 in the manner described hereinbefore. Thus, the time whenamplifier section 2|! becomes again conducting is determined solely bythe frequency of pulses 48 developed by quench oscillator 2. On theother hand, the average or direct current grid voltage during the periodof oscillation of amplifier sec- 'tion |I depends on the amplitude ofinput wave 53. Thus, when the input wave has the amplitude illustratedat 53 in Fig. 2, the average grid voltage follows curve 55. On the otherhand, when the amplitude of the input wave is larger as shown at 56,theaverage grid voltage is given by curve 51, and if the amplitude of theinput wave should be smaller than that illustrated at 53, the averagegrid voltage would be given by dotted curve 58.

Since the average grid voltage determines the average quench current, itwill be seen that the' amplitude of the quench frequency current ismodulated in accordance with the amplitude of the carrier wave impressedupon regenerative amplifier I. If the time of conduction of ampliiiersection 20 is comparatively long as villustrated in Fig. 2, the averagequench current will vary in accordance with the amplitude of the inputwave. If, however, the time of conduction of amplifier section iscomparatively short, both the average and the peak quench current willvary in accordance with the amplitude of the modulated carrier waveimpressed on input circuit 8.

The amplitude-modulated quench current may .-i now be detected byVdetector 3. The modulated quench current derived from output lead 2 isfiltered by resistor and blocking condenser 6| "connected to primarycoil 62 having its low alderived from regenerative amplifier has its amlplitude modulated, detector input circuit 53, 64

may be tuned to the quench frequency. Thus, the tuning of amplifierinput circuit 1 and detector input circuit 63, 64 are independent ofeach other. The super-regenerative receiver in accordance with thepresent invention as illustrated in Fig. 1, therefore, has unexpectedadvantages over the super-regenerative receiver disclosed in the priorKoch patent. It is to be understood that any conventional quenchoscillator may be substituted for quench oscillator 2.

Referring now to Fig. 3, in which like components have been designatedby the same reference numerals as were used in Fig. l, there isillustrated a super-regenerative converter in accordance with thepresent invention which may be utilized as an angle-modulatedcarrier-wave adaptor for an amplitudefmodulated carrier- Wave receiver.Regenerative amplier I and quench oscillator 2 of Fig. l also functionsas a super-regenerative convertor. The angle-modulated carrier wave maybe intercepted by antenna 19 which, as illustrated, may be a dipoleantenna, arranged for receiving a high-frequency carrier Wave. Y K

The intercepted angle-modulated carrier wave is impressed on primarycoil 6 inductively coupled to secondary coil 8 of input circuit 1, whichmay be tuned by variable condenser I0. The separate quench regenerativeamplier comprises amplifier sections I I and 20 which may be separatetriodes as illustrated, or twin triodes. Am pliiier sections Il and'2esimultaneously function as a regenerative amplifier and quenchoscillator. Amplifier section Ii has its cathode I connected to groundthrough cathode resistor It. The modulated carrier wave impressed uponin put circuit 1 is impressed on control grid I2 through grid couplingcondenser i3. Grid leak resistor 1I is connected between control grid I2and cathode I5. Anode I1. of amplifier section II is connected to thepositive voltage supply +B through anode resistor 12. Y

Ampl'mer section 20 has its cathode 2I tied to cathode I5 and connectedto ground 'through cathode resistor I6. Control grid 22 is connected toground through resistor 4I, bypassed by condenser Furthermore, controlgrid 22 is connected to anode I1 through the series combination ofcondenser 44 and resistor 43. The junction point between resistor 133and anode l1 is bypassed to ground by carrierfrequency bypass condenser13. Anode 23 of amplifier section 29 is connected to the positivevoltage supply +B through anode resistor 25. Furthermore, anode 23 iscoupled to control grid I2 by blocking condenser 26 and grid couplingcondenser I3.

The separate quench regenerative amplifier I I, 2d functions essentiallyin the same manner as regenerative amplier l and quench oscillator 2 ofthe circuit of Fig. 1. Thus, control gridA i2 is grounded for currentsat the quench frequency, that is, at the frequency developed by thequench oscillator. On the other hand, control grid 2i. is grounded forcurrents at the frequency of the carrier wave. determined by theconstants of the networks including the series combination of resistor43, condenser 4fi, and the parallel combination of resistor 4I andcondenser 42.

The quench current which has its amplitude modulated in accordance withthe amplitude of. the input wave may be derived across cathode resistorI6. The super-regenerative receiver of Fig. 3 preferably is arranged forreceiving an angle-modulated carrier wave. In that case, input circuit 1may be tuned Qif the center fre-Y quency of the carrier wave so that thecircuit functions as a frequency-discriminator network.

The amplitude modulated quench current. may be obtained from lead 21connected to the junction point between cathodes I5, 2i and cathoderesistor I6. The signal may be impressed upon antenna of a conventionalamplitude-modulated carrier-wave receiver through lter resistor 5@ andblocking condenser 6 I The quench frequencypreferably is superaudibleand may be. between approximately and kilocycles. Assuming that thequench frequency is 40 kilocycles, radio frequency ampliiier andconverter 16 may. for example, be tuned to Thev quench frequency isagain the fourteenth harmonic of the quench frequency, that is, to 560kilocycles or to any other desired harmonic. A large number of theharmonics of the quench frequency will fall within the tuning range of aconventional broadcast receiver. Once it has been determined Whichharmonic of the quench frequency will be utilized, variable condenser 11may be tuned by tuning knob 18 to that frequency and need not beadjusted any more. Variable condenser 11 schematically indicates thetuning condenser of the input circuit of the radio frequency amplierstage and of the local oscillator.

The intermediate frequency wave developed by converter 16 may beamplified by intermediatefrequency amplifier and may then be detectedand further amplied by detector and audio amplifier 8|. The amplifiedaudio signal may be reproduced by loud speaker 82.

It will thus be seen that when a regenerative amplier having a separateoscillator is utilized as an angle-modulated carrier-wave adaptor,tuning of amplifier input circuit 1 will be independent of the tuning ofvariable condenser 11 which tunes the input circuit of theamplitudemodulated carrier-wave receiver. Since the entire amplificationavailable in an Y amplitudemodulated carrier-wave receiver is utilized,the amplification of the super-regenerative adaptor need not be verylarge. It is also feasible to provide a radio-frequency amplier stageahead of the regenerative amplier in order to minimize undesiredradiation by the super-regenerative receiver.

Referring now to Fig. 4, there is illustrated a super-regenerativereceiver including a regenerative amplifier having self-quenchingaction. The receiver of Fig. 4 may also be used with advantage as anangle-modulated carrier-wave adaptor for a conventionalamplitude-modulated carrier-wave receiver. Self-quenching regenerativeamplier includes amplier sections S6 and 81. Amplier section 85 isprovided with cathode 84, control grid 88 and anode 9D. Cathode 84 isconnected to ground through cathode resistor SI. The inputsignalimpressed on input circuit 1 is impressed on control grid B8through grid coupling condenser I3. Grid leak resistor 92 is connectedbetween control grid 88 and cathode 84. Anode 90 is connected to asource of positive voltage indicated at +B.

Amplier section 81 comprises cathode 93, control grid 94 and anode 95.Cathode 93 is tied to cathode 84 and connected to ground through cathoderesistor SI Controlgrid 94 is connected to ground whilel anode 95 isconnected to the posi tive voltage supply +B through anode resistor 25,bypassed to ground through bypass condenser 96. Anode 95 is furthermorecoupled to control grid 88 through blocking condenser 26 and gridcoupling condenser I3. The output signal may be derived across cathoderesistor 9| and may be obtained by lead 21, lter resistor 60 andblocking condenser 6I. It is to be understood that blocking condenser 6Imay be connected to the antenna of an amplitude-modulated carrierwavereceiver in the manner illustrated in Fig. 3.

The super-regenerative receiver of Fig. 4 preferably is arranged forreceiving an angle-modulated carrier wave. The angle-modulated carrierwave intercepted by antenna 1i) is impressed through primary coil 6 ontuned input circuit 1- where itis transformed into a correspondingamplitude-modulated carrier wave.v This is effected in the mannerdescribedin. the Koch patent referred 4to by tuning input .circuit 1slightly offthe centerfrequency of the carrier wave so that the slopevof the resonant curveA of circuit. 1 ,will change Variations ofthefrequency of the anglemodulated wave into'correspo'nding variations ofits amplitude. A l

The operation of self-,quenching regenerative amplifier 85 may best beexplained by reference to Fig.r5 illustrating the voltage of controlgrid 88 plotted with respect totime. Let it bef assumed that amplifiersection 86 is conducting space current. Hence the current flowingthrough common cathode resistor 9llwill:causefai-voltage dropthereacross which ywill raisethe-"potential oi cathode 93. This willcause termination of the space current through amplier section 81 with acorresponding rise of the voltage of anode 95. This positive voltage isimpressed upon control grid 88 through blocking condenser 2B and gridcoupling condenser i3. The positive charge impressed upon couplingcondenser I3 is rapidly dissipated by the space current iiowing throughamplifier section 85 as indicated by curve |00 in Fig. 5. Dash lineindicates the zero voltage while line |02 indicates the grid cut-offvoltage, that is, the bias voltage required on control grid 88 for zeroplate current. It will be noticed that curve |00 represents the directcurrent voltage of control grid 88 which is below grid cut-off voltage|02. Ampliiier section 86, however, is maintained conducting because thesum of the alternating current voltage and of the direct current gridvoltage indicated by curve |03 periodically reaches the grid cut-offvoltage shown by line |02.

Curve I 03 represents the oscillation at the carrier frequency whichbuilds up in input circuit 1. At a certain instant indicated by line|09, the direct current grid voltage becomes so negative with respect toground that space current can no longer be maintained in amplifiersection 86.

The potential of cathode 93 accordingly rises again, and amplifiervsection 81 will now conduct space current. The negative voltageexisting at that instant on grid coupling condenser I3 is slowlydissipated through grid leak resistor 92, and condenser I3 is dischargedthrough cathode resistor 9|,y ground and secondary coil 8. In themeantime, the oscillations previously built up in tuned input circuit 1are rapidly damped as indicated by curve |03. The time constant of gridcoupling condenser I3 and of grid leak resistor 92 is such that theoscillations in input circuit 1 are reduced to a low value beforecoupling condenser i3 is discharged to such an extent that conduction ofamplifier section 86 may be initiated again.

Conduction of amplier section 86 is initiated again by the input signal,that is, by the anglemodulated carrier wave illustrated in Fig. 5 bycurve |04. It is to be understood that input signal |00 is alwayspresent on control grid 88 but has only been illustrated during aportion of the quench cycle in order to avoid confusion. As soon as thevoltage of input signal |04 reaches grid cut-off voltage |02, ampliersection 86 begins to conduct space current again, and the cycle ofoperation is repeated.

If during the next quench cycle the amplitude of the input wave issmaller as indicated by curve |05, it will be seen that ampliiiersection 86 is triggered at a later time during the quench cycle so thatthe period of time indicated by arrow |06 when amplifier section 86 isnot conducting is shorter than the period of time |01 during the -nextquenchcycle when ampliiier section B'B is not conducting space current.

'It will 1accordingly be seen that the amplitude .of theY modulatedvcarrier wave determines the time when amplier section 86 is triggeredand consequently the quench current derived across cathode resistor 9|is frequency modulated. A harmonic of the frequency modulated quenchcurrent derived across cathode resistor 0| may be impressedl throughfilter resistor and blocking condenser 6| upon the antenna of anamplitude-'modulated carrier-wave receiver in the manner illustrated inFig. 3.

The super-regenerative receiver of Fig. 4 has the d awback that theytuning of regenerative either have its amplitude modulated inaccordance with the modulation signal, or alternatively, anangle-modulated carrier wave may first be transformed directly intoacorresponding amplitude-modulated carrier Wave which controls themodulation of the quench current. As illustrated in Fig. 1 theamplitude-modulated quench current may be detected to derive themodulation signal. Alternatively, as shown in Fig. 3 a harmonic of theamplitude-modulated quench current may be selected which may be furtheramplied before being detected. The super-regenerative receiver of Fig. 3may therefore be used with advantage as an angle-modulated carrier waveadaptor or converter for a conventional amplitude-modulated carrier-Wave receiver.

Another type of angle-modulated carrier-wave adaptor has been disclosedin Fig. 4. Here, the regenerative amplifier is of the self-quenchingtype and accordingly develops a frequency-modulated quench current. Aharmonic of the quench current may be selected and transformed into acorresponding amplitude-modulated quench wave. This harmonic wave maythen be further amplified and detected. The super-regenerative receiverof Fig. 4 may therefore also be used with advantage as anangle-modulated carrierwave adaptor for an amplitude-modulatedcarrier-wave receiver.

What is claimed is:

1. A method of demodulating an amplitudemodulated carrier wave whichcomprises regenerating said wave and interrupting the regenerationperiodically at a constant super-audible frequency, controlling thefrequency of the developed quench current in accordance with variationsof the amplitude of said wave, selecting a harmonic of saidfrequency-modulated quench current, and demodulating said harmonic todevelop the modulation signal.

2. A method of demodulating an angle-modulated carrier wave whichcomprises translating said angle-modulated carrier wave into acorresponding amplitude-modulated carrier wave, regenerating saidamplitude-modulated carrier iva-Ve and interrupting the regenerationperiodically at a constant frequency, controllingY the frequency of thedeveloped quench current in accordance with variations of the amplitudeof'said amplitude-modulated carrier wave, selecting a harmonic of saidfrequency-modulated quench current, and demodulating said harmonic todevelop the modulation signal.

WINFIELD R. KOCH.

REFERENCES CITED The followingr references are of record in the le ofthis patent:

UNITED STATES PATENTS Name Date Nyman Jan. 25, 192'? Number OTHERREFERENCES Kalmus, Some Notes on Superregeneration, Proc. IRE, October1944, pages 591 to 600.

